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UW-Madison NUTRSCI 132 - Bone Health

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NUTR SCI 132 Lecture 28 Outline of Last Lecture I. Red Blood Cellsa. Anemiab. Ironc. Vitamin KII. Energy Releasea. B Vitaminsb. Bone Healthi. Remodelingii. CalciumOutline of Current Lecture I. Bone Healtha. Calciumb. Phosphorusc. Vitamin Dd. Vitamin Ke. OsteoporosisCurrent LectureI. Bone Healtha. Calciumi. Low Calcium Intake1. PTHa. Kidney activates D precursori. Tells Mucosa to Increase Ca Absorption (Increase Absorption from gut)1. Blood Ca Increases2. PTHa. Stimulates osteoclastsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. Dissolve bone and matrix (Reabsorption of Ca from bones)1. Release Caa. Blood Ca Increasesii. High Blood Ca Intake1. High Blood Caa. Thyroid releases calcitonini. Stimulates osteoblasts1. Build bonea. Take up Ca from Bloodiii. Blood Calcium maintained (at any cost to the bone!)1. Breathing (muscular contraction) much more important (immediate) than poor bone health down the roada. High Ca Intakei. Build new boneb. Low Ca Intakei. Meet Ca need by dissolving bone and releasing Caiv. Factors affecting Ca status1. Negative Ca Balancea. Urinary Lossi. Diuretics1. Caffeine2. Alcohol3. Excessive Proteinb. Fecal Lossesi. High intake Phosphorus (Soda!)1. Ca passes through body unabsorbedc. Smokingi. Lowers Estrogenb. Phosphorusi. Part of hydroxyapatiteii. High need1. Ubiquitousa. More concerned with getting too much than too littlec. Vitamin Di. Necessary for Ca absorptionii. Precursor synthesized in skin from cholesterol using UV light1. Activated in kidneya. D acts on mucosaiii. Deficiency1. Unable to absorb Caa. Ricketsi. Growing childrenii. Bones don’t develop properly (curved)b. Osteomalaciai. Adultsii. Bones weakened, break easilyiv. Toxicity1. Second easiest vitamin to get toxicity from!a. Too much Ca absorbedi. Blood Ca too High1. Ca deposited in kidneys, soft tissuesd. Vitamin Ki. Osteocalcin1. Bone metabolismii. Low Vitamin K intake >> Increase fracturese. Magnesiumi. Most found in bone (stored here)ii. Enzymesf. Other Factorsi. Exercise1. Weight-bearing Exercise (walking, running, etc.)a. Bone adapts to stressb. Increases Bone Strength2. Cycling and swimming do NOT strengthen bones3. Weight Training good4. Jumping is best!a. Plyometricii. Amenorrhea1. Cessation of Menstruationa. Low Body Fati. Decreases Estrogen1. Bone Lossa. Osteoporosis2. Female Athlete Triada. Low Body Fat (and Low Estrogen)i. High Levels of trainingii. Low fat dietiii. Eating Disorderb. Prevalenti. Sports that place premium on low body weight1. Ballet, gymnastics, distance runningg. Osteoporosisi. Elderly shrink!ii. Hip fractures1. Huge quality of life issuea. Lose Independenceiii. Imbalance1. Bone Formation and Reabsorption of Mineral from Bonea. Reabsorption > formationi. Negative Calcium Balanceiv. Porous, weakened bone1. Most people will get this if they live long enough!a. How fast is it happening?i. In some people, the process is slow enough that they don’t see problemsv. Contributing Factors1. Menopausea. Estrogen protects boneb. Decrease estrogen2. Less Vitamin D in elderlya. Decreased synthesis of precursorb. Less sun exposurei. Less efficient activation of precursor in kidneyc. Mucosa cells less sensitive to Vitamin Di. Less Vitamin D1. Decreased Ca absorption2. Ca comes from boned. Not just D deficiencyi. Osteomalacia1. Loss of mineralii. Osteoporosis1. Loss of mineral AND matrix3. Low Ca intake (over time!)a. Good intake is necessary, but still no guaranteevi. Prevention1. Build mineral reserves early in life, then maintain thema. Bone mass peaks ~35yrs2. How?a. Good balanced dieti. Adequate Ca, D, K1. Massive Ca supplement does not work well!ii. Not excessive Caffeine, alcohol, proteinb. No smokingc. Weight bearing


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